On top of ballet, the gym, and the odd yoga class, columnist Katy gives Pilates a whirl to tone up her midrift.

First it was ballet, then yoga, and then, a month or so ago, I started Pilates classes. I'd been given a book about Pilates - the exercise system devised by Joseph Pilates in the early part of the 20th century - ages ago and knew the exercises were meant to be fantastic for strengthening your core muscles, i.e. your stomach, back, thighs etc, so I thought I'd sign up for a six-week course as there was no way the book was every going to get used.

Juliette Wilnis has been running one-to-one classes from her Ipswich home for some time but not quite able to afford such intimate intuition, I thought I'd start her group sessions at a local primary school.

So I turned up (slightly late as I could not find the school) in my tracksuit and bowled into the hall where half a dozen 30-40-year-old women were awaiting tuition.

The first lesson was quite slow-going and I certainly didn't break out into a sweat, but this was due to Juliette taking us through each move thoroughly so we got the basics right, building up a solid foundation for future weeks.

The vast majority of the moves do seem to involve the stomach muscles and I have definitely seen an improvement to the tone of my six pack (well, more like four pack), although I'll have to stop the chocolate binges if I'm to remain flat bellied (I knew I should have quit for Lent, as I normally do), or a layer of fat will cover the newly found muscles.

Anyway, all the movements are very slow and controlled - a far cry from the energetic, momentum-fuelled stomach crunches I see performed by so many people at the gym. If only they knew about Pilates they'd see much faster results.

The obliques exercise is one of the hardest. You have your head cupped in your hands and your knees bent; you raise your shoulders slowly and then, trying not to move from your shoulders, twist to one side. The aim is to twist the rib cage, engaging the side muscles rather than cheating and just turning your head and shoulders. To an observer it looks like we are hardly moving and not doing much, but trust me, when you get it right your stomach is crying out; my top half often starts juddering, meaning the muscles are overloaded and working hard!

One of the exercises I'm less keen on is the torpedo, where we lie on one side, stretched out like a plank of wood, and have to lift our legs up. This is another stomach exercise but it hurts my hip so I have to place a cushion underneath - that and I always seem to roll forwards!

During the class, various pieces of equipment are used, from half-deflated balls (which you either rest your head on or squeeze between your knees to give your thighs a good workout) and those stretchy bands. The best one is where you lie on the floor with one leg raised and the band looped over your foot, while pulling down on the band and stretching your leg as straight as possible. It hurts like hell but afterwards, your legs feel great.

The lessons have definitely been getting harder as we've gone along and the moves become more challenging each time. I've no doubt that if I continued on a regular basis, my stomach would improve no end. Sadly though, I'm not sure I can afford to sign up for another six weeks due to some rather astronomical bills which landed with a thud on my door mat a few weeks ago. So perhaps I'll just try and do the moves at home and dig out that book that's been sitting on the shelf for years. All I need is the motivation, which is hard to muster at home when faced with a comfy sofa and a cupboard full of chocolate.